1. Field of the Invention
This invention relates to an automatic plug-in connecting apparatus for supplying an electric current from a power source, capable of being used in a hazardous area for explosive gas atmosphere, for example, a combustible and inflammable gas atmosphere.
2. Description of the Prior Art
As the automation of machines and the saving of human power have progressed in the general industrial field, a demand that the connection and disconnection of a power source current supply line be carried out automatically has increased, and various types of automatically detachable plug-in connecting apparatuses have been developed and put to practical use. However, an automatically detachable plug-in connecting apparatus of an explosion-protected construction capable of being used in such a hazardous area as mentioned above is still under development.
Although a plug socket of a flame-proof type explosion-protected construction has heretofore been sold on the market as a device for connecting a machine to a power source current supply line in such an explosive gas atmosphere as mentioned above, it cannot be utilized as an automatic connection and disconnecting device since it carries a high price and large weight, and since it is designed with a dust-proof cap. Additionally, the centering of a plug and socket as well as the fixing of the plug and socket union must be carried out manually.